Well I've made one side.
As I'm an impatient git I cut the shape with a grinder and cut the oval centre out with the hole saw.
I sandwiched the metal between 2 sheet of Mdf and just drilled it out the cleaned up the middle with a grinder.
This is my first ever attempt at welding and I did about 5 practice lines before getting bored and going for it.
I've never picked up a welder before today so be kind lol.
It doesn't look great but I will grind it down and seam sealer it anyway so you won't see it when I'm done.

Hole cut out and cleaned

New plate made and cleaned


Rested on top for good measure The plate is about 10mm bigger than the hole all round so I could have 2 overlap welds, 1 on top and 1 below.


Plate fitted underneath and All welded up



Welding getting slightly better lol


Underneath



And finished.



Only grinded it down a bit as its late.
Will clean it up and Seam sealer it later.

Overall I'm very happy with it.
Especially as Its my first attempt.